In order to meet the National Cancer Institute's year 2,000 goal of reducing cancer deaths by 50 percent, groups in society who are chronically underinformed and underserved will need to be reached more effectively. This first twoyear phase of a more comprehensive research program will focus on the cancer knowledge and service gap among blacks. The theory under investigation is the knowledge gap among blacks. The theory under investigation is the knowledge gap conceived of as the difference in knowledge levels between the advantaged and disadvantaged in a social system which appears to increase rather than decrease as more information is infused into the system. Alternative explanations for the knowledge gap will be examined by comparing black cancer information seekers (operationalized as those who call the Cancer Information Service (CIS) with blacks who have not used the CIS. In addition we will explore specific communication issues, such as credibility of sources, effectiveness of motivational appeals, and patterns of media consumption to recommend strategies to cancer communicators for narrowing the knowledge gap. The research has three phases. In phase one, the available data on black callers to the Cancer Information Service from 1983 through 1986 will be analyzed and reported in a paper to be presented at a professional meeting and published in an academic journal. In phase two, all available literature (including several surveys) on blacks' knowledge, attitudes, and practices regarding cancer will be collected, analyzed, and reported in a presentation at a professional meeting and published in an academic journal. In phase three, original data will be collected with a survey of two groups of blacks--those District of Columbia residents who have called the Cancer Information Service and those who have not. These data should help us understand the knowledge gap by answering such questions as: does the knowledge gap exist in the black audience? Is it a result of low socioeconomic status or ethnic identity? Can the knowledge gap be explained by lack of motivation, lack of access to information, or distrustfulness rather than by education? Moreover, these results should yield some pragmatic guidelines for reaching this priority audience with cancer information.